Combined technique analysis of the composition of Punic make-up materials

Ten archaeological Punic make-up samples from Tunisia dating from the 4th to the 1st centuries BC were analysed by several techniques including Raman microscopy and synchrotron X-ray diffraction in order to determine their compositions. Eight samples were red and found to contain either quartz and cinnabar or quartz and haematite. The remaining two samples were pink, the main diffracting phase in them being quartz. Examination of these two samples by optical microscopy and by illumination under a UV lamp suggest that the pink dye is madder. These findings reveal the identities of the materials used by Carthaginians for cosmetic and/or ritual make-up purposes. PACS 82.80.Gk; 61.10.Nz; 41.60Ap     

XAFS study of copper and silver nanoparticles in glazes of medieval middle-east lustreware (10th–13th century)

It has recently been shown that lustre decoration of medieval and Renaissance pottery consists of silver and copper nanoparticles dispersed in the glassy matrix of the ceramic glaze. Here the findings of an X-ray absorption fine structure (XAFS) study on lustred glazes of shards belonging to 10th and 13rd century pottery from the National Museum of Iran are reported. Absorption spectra in the visible range have been also measured in order to investigate the relations between colour and glaze composition. Gold colour is mainly due to Ag nanoparticles, though Ag⁺, Cu⁺ and Cu²⁺ ions can be also dispersed within the glassy matrix, with different ratios. Red colour is mainly due to Cu nanoparticles, although some Ag nanoparticles, Ag⁺ and Cu⁺ ions can be present. The achievement of metallic Cu and the absence of Cu²⁺ indicate a higher reduction of copper in red lustre. These findings are in substantial agreement with previous results on Italian Renaissance pottery. In spite of the large heterogeneity of cases, the presence of copper and silver ions in the glaze confirms that lustre formation is mediated by a copper- and silver-alkali ion exchange, followed by nucleation and growth of metal nanoparticles.     

Study of sulphation of Candoglia marble by means of micro X-ray diffraction experiments

This research is aimed at assessing the particular kind of damage caused by the interaction between atmospheric pollution and the marble surface of a magnificent late gothic church, Milan Cathedral, restored in the early 1970s. On the basis of visual inspections and diagnostic investigations the facade appears to be seriously damaged by surface erosion and thick black crusts; biological crusts, micro-fractures and detachments are widely present.This paper reports on SR-μXRD data collected at the Synchrotron Radiation Source (SRS), Daresbury Laboratory, and at the European Synchrotron Radiation Source (ESRF) from selected samples, covered with black crusts, originating from the Milan Cathedral facade. Mineralogical maps of the deterioration layers have been recorded by two spatial resolutions (5–100 μm), from the bulk of the stone material to the outer layer of the black surface. These maps help in elucidating the mechanism of formation of the black crusts. PACS 33.20.Rm; 61.10.Eq; 61.10.Nz; 78.70.Ck     

Vinylogous Reactivity of Cyclic 2‐Enones: Organocatalysed Asymmetric Addition to 2‐Enals to Synthesize Fused Carbocycles

A method for asymmetric and site selective annulations at the γ and γ′ positions of cyclic 2‐enones with α,β‐unsaturated aldehydes has been developed. The organocatalysed [3+3]‐annulations proceed with high levels of regio‐, diastereo‐, and enantioselectivity, affording a series of high value fused carbocycles. Further elaboration gave key lactones (both bridged and fused).     

Selective Isomerization of Epoxides to Allylic Alcohols Catalyzed by TiO2‐Supported Gold Nanoparticles

ReacTiO ₂ ns for rings : Gold nanoparticles supported on TiO₂ are used as a novel heterogeneous catalyst for the isomerization of epoxides to allylic alcohols by a concerted mechanism (see scheme). The reaction proceeds in high yields and the product selectivity is often remarkable.

     

Solvent-dependent changes in the ene reaction of RTAD with alkenes: the cyclopropyl group as a mechanistic probe

[reaction: see text] The vinylcyclopropyl moiety was used as an efficient probe to test mechanistic possibilities of the triazolinedione-alkene ene reaction. In non-hydroxylic solvents, this reaction afforded only the ene adducts via a closed three-membered aziridinium imide (AI) intermediate, whereas in hydroxylic solvents a dipolar intermediate is favored and trapped by the cyclopropyl moiety to form the corresponding cyclopropyl-rearranged solvent-trapped adducts.     

Detection of the ππ* E2g state in sym-tetrafluorobenzene

The VUV absorption spectrum of gaseous 2,3,5,6-tetrafluorobenzene is reported up to its first IP. The absolute extinction coefficient and f value are given. A band appearing at 6.85 eV is attributed to the E_2g benzene parent state with f = 0.06. A similar band is found in 1,3,5-trifluorobenzene, where the E_2g ← A_1g transition is symmetry allowed.